Oil return arrangement



Dec. 12, 1944. M. B. GODDARD ETAL OIL RETURN ARRANGEMENT Filed Oct. 31,1940 MERRILL B. GODDARD INVENTOR5 AND RICHARD C. OELER Patented Dec. 12,1944 UNITED STATES PATENT OFFICE.

on. RETURN ARRANGEMENT Merrill B. Goddard and Richard C. Oeler, Chlcago,Ill., assignors of one-half to Carrier Corporation, Syracuse, N. Y., andone-half to The Liquid Carbonic Corporation, Chicago, Ill.

Application-October 31, 1940, Serial No. 363,712

Claims. (Cl. 62-115) This invention relates to refrigeration systems andmore particularly to an oil return arrange-v ment employed in connectionwith flooded systems wherein the oil mixes with the refrigerant. Thegeneral object of the invention is 'to pro vide for the return of oil toa compressor from ie low side of a flooded refrigeration system whereinthe efliciency of the system will be subciated with the cooler orevaporator, but such prior practices have not always been satisfactory,especially under varying load conditions, and in' some cases, the'expedients employed required the use of needle valves, solenoid valvesand the like, all of which are eliminated by applicants in theirsolution of the problem.

A feature of the invention resides in the provision of a simpleaccumulator structure operatively associated with a cooler .foreffectively feeding oil back to the compressor, the amount of oil fed tothe suction line of the compressor being proportional to the suctionvelocity or speed of the machine. Thus, under heavy loads, when thecompressor operates at higher velocity, more oil will be led backthan'under low load conditions when the compressor speeds are lower. Ineffect, *the amount of oil returned always meets the-requirements ofoperation despite varying load conditions.

A further feature of the invention resides in the provision of an 'oilreturn arrangement wherein the return of oil to a compressorautomatically terminates when the compressor becomes inoperative, thuseliminating the dangers of rupture as might occur from a continuation ofbleeding back of liquid to a compressor, especially of the reciprocatingtype.

Further features making for eflcientoperation, simplicity and economy inconstruction,

and substantial freedom from service troubles,

will be apparent from the following description of one form of theinvention to be read in connection with the accompanying drawing, drawnto diflerent scales, in which:

Fig. 1 illustrates a flooded system incorporating an accumulator inwhich applicants oil return arrangement is employed, and Fig. 2 is a.sectional view diagrammatically illustrating that portion of theaccumulator in which the oil return structure is provided, and

Fig; 3 is a fragmentary plan view illustrating certain features of theaccumulator structure.

Referring to the drawing, similar designations referring tosimilarparts, numeral 4' generally designates a refrigeration system of theflooded type utilized, for example, for the cooling of water. Acompressor-condenser assembly is diagrammatically lllustrated andincludes compres sor base 5 on which is mounted motor 6 for drivingcompressor I, which is shown to be of the reciprocating, although it maybe of any other, type. Although, one cylinder is diagram-,

matically shown, it will be understood that the machine may be amuiti-cylinder structure, the construction of which is well-known in theart, and the details of which are eliminated, since ,they form no partof the invention. Condenser the invention. The-liquid refrigerant plussuch oil as is lost past the piston rings or is otherwise in the system,passes under high pressure from receiver 9 to heat exchanger l0, thenthrough injector ll into cooler l2. From the cooler, the evaporatedrefrigerant plus liquid refrigerant plus such oil as is carried overenters accumulator l3 and the evaporated refrigerant (including aportion or such oil) is then returned to the compressor through heatexchanger Ill, back pressure regulator valve II, and suction line IE, tocomplete the cycle. The cooler or evaporator l2 serves a cold storagetank It from which water may be fed through cold water discharge line I]for any desired 'purpose, the cold water tank being equipped with alevel control l8, and overflow pipe I! to provide a practical cold watersupply system.

Considering the accumulator arrangement IS, a mixture of liquid andgaseous refrigerant in practice enters accumulator l3 from: theevaporator through line 20. This mixture also contains a portion of oilwhich has been carried over intothe system. The purpose of theaccumulator is to cause a separation of the liquid from the gaseousrefrigerant so that the liquid may bereturned to promote furtherrefrigerating effect and the gas returned to the com- 66 pressor.

' operation, only gaseous to a compressor,

' free from possible clogging due to With applicant's accumulatorstructure, the liquid will settle to the bottom of accumulator l3 andwill return through liquid leg 2| to in-.

jector II for recirculation to cooler 12. The gaseous refrigerant issucked from the accumulator through return line 22- which is actuallypart of suction line [5.

To prevent excessive liquid refrigerant from being sucked into line 22at the entrance point 23, a baflle 24 is positioned about-line 22 at theentrance end thereof. A flange or lip 25 is provided at the periphery ofbaflie 24 to form a cup or shallow receptacle. Access from the cup toline 22 is through an orifice 26.

In practice, a rush of liquid and gaseous refrigerant, containing asmall amount of oil, enters theaccumulator through line 20. Such liquidas is routed between the cup and the inner wall 21 of the accumulatordrops to the bottom thereof for return to the injector through leg 2|.Gaseous refrigerant above the liquid level in the accumulator is suckedinto line 22 for return to the machine.

It may here be noted that if gaseous refrigerant were alone taken intothe suction line 22, with the oil remaining behind in the low side ofthe I I it must be fed in small quantities and substantially free ofliquid refrigerant. Also, such'return of liquid would result in possibledamage to the compressor and hence, soon necessitate stoppingoperations.

To avoid the possibility of such undesirable the accumulator is sodesigned that refrigerant plus a desired metered quantity of oil isallowed to pass to the compressor. The baffle arrangement withinaccumulator l3 catches'oil and refrigerant to form a small source ofsupply to the compressor. In effect, only that small amount of liquidrefrigerant, containing oil, which passes through orifice 26, is suckedinto line 22. When this reaches heat exchanger l0 and comes in indirectcontact with the hot liquid flowing therethrough from the high side ofthe machine, the refrigerant will in effect be boiled out and will reachthe compressor, after leaving the heat exchanger, in gaseous superheatedcondition. The oil, in liquid form, carried over into the compressor,with the seous refrigerant, is free of liquid refrigerant, "and in aform to be accepted by the compressor for return to the crankcase.

Thus, applicants have provided a safe method of feeding a small amountof liquid containing oil but have assured the gasification of the liquidrefrigerant in its course to the compressor so that the oil free ofliquid reaches the compressor with the refrigerant fed to the compressorin gaseous form. The cup construction provides an adequate reservoir forcontinuous flow of liquid containing oil through a fixed orifice. 'I'heprojecting lips 28 oneach side of orifice 26 form a pocket wi hin whichliquid'is collected for continuous flow through the orifice while thesystem is in operation. 'The lips prevent sweeping away of liquid fromthe orifice. Interruption in the continuity of flow through the orificeis thus avoided. Screen 29 serves to keep the orifice particles cartheresult would be an increasing con-' hence, more liquid will be fed backunder heavierload conditions than when the compressor speed is lowerunder lower load conditions. Thus, the

, rate of return increases and decreases responsive to increases anddecreases of load conditions andv assures a check on contamination inthe system regardless of variations in load.

When the compressor shuts down, it will be impossible for the liquid tobe returned to the The bleeding back automatically place the smallamount of isdownwardly from 26 into the bottom of compressor. ceasessince the only accumulated liquid can go the cup through the orifice theaccumulator. This of feeding liquid back to the compressor which mightcause blowing of a cylinder head or other damage.-

It may be noted that no valves are employed to throttle the fiow ofliquid to the suction line, as

is customary in some prior arrangements; nor do applicants require asolenoid valve or similar arrangement, often employed in such systemsfor stopping flow of liquid when the compressor stops.

It is apparent that applicants system of oil return is applicable toalltypes of flooded systems and hence, it is intended that all mattercontained in the above description or shown in the accompanying drawingshall be interpreted as illustrative and not in a limiting sense.

We claim: I l.'In a flooded refrigeration system, a compressor, acondenser, and an evaporator, operatively associated having oil toentrained therein to the accumulator I from the evaporator, a heatexchanger, means for withdrawing liquid refrigerant from the accumulatorfor return to the evaporator, means subjected to variations in suctionpressure for withdrawing from the accumulator a varying quantity ofrefrigerant and oil and admitting the same to the heat exchanger, saidrefrigerant being gasifled in the heat exchanger, and means forreturning the gaseous refrigerant and oil entrained therewith to thecompressor from the heat exchanger.

3. In a compression refrigeration system containing a refrigerant andasupply ofoil, an accumulator, means for feeding a portion of saidrefrigerant with a portion of said oil entrained therein to theaccumulator, means for withdrawing refrigerant with entrained oil fromthe ac cumulator consisting of aline having an inlet below the liquidlevel in the accumulator, a second line leading from within theaccumulator, said second line having an inlet above the liquid level inthe accumulator, means for admitting a measured quantity of refrigerantwith entrained oil from the accumulator into said second line. the

eliminates any possibility together, an accumulator, means for admittingrefrigerant having oil entrained aaomsa the second line and means forremoving the resultant gas and oil entrained therewith from saidgasifying means for further use in the system.

4. In a system of the character described, a compressor, a condenser andan evaporator operatively associated to carry on a refrigeration cycle,an accumulator, means for admitting refrigerant having oil entrainedtherein to the accumulator from the evaporator,'an injector for feedingliquid body of liquid below the receptacle, means responsive to suctionpressure in said line for feeding a measured quantity of the liquid fromsaid receptacle into said line.

7. In a system of the character described, an accumulator, means forfeeding refrigerant with entrained oil into the accumulator, a suctionline refrigerant supplied from the condenser to the evaporator, meansfor feeding liquid refrigerant from the accumulator to said injector, acollecting device within the accumulator, a measuring device throughwhich liquid from said collecting device may be withdrawn, a suctionline leading from a point above the liquid level in the accumulator andconnecting said measuring device to the suction intake of thecompressor, liquid refrigerant and oil entrained therewith being fedfrom said measuring device into said line responsive to suction pressureexerted on the line by said compressor, a

5. In a system of the character described, a compressor, a condenser, anevaporator, a heat interchanger, means for feeding refrigerant from thecondenser to the interchanger, a line connecting the interchanger andevaporator for feeding refrigerant to the latter, an accumulator, meansfor feeding refrigerant with entrained oil leading from within theaccumulator to a compressor, a cup-shaped receptacle within theaccumulator, said line passing through the receptacle, an orificeconnecting the receptacle to said line, gaseous refrigerant being fedinto said line from the accumulator, liquid refrigerant with entrainedoil being fed into said line through the orifice. I

8. In an accumulator arrangement according to claim 7, said cup forminga reservoir surrounding said line, and a plurality of lips within saidcup forming a pocket about said oriflce to prevent liquid adjacent saidorifice from being swept away.

9. In combination for use in a flooded system of the characterdescribed, a casing, a first line for supplying refrigerant from a pointof evaporation to said casing, a second line leading from the casing, athird line leading from the casing, a

to the accumulator from the evaporator, means for returning a portion ofsaid refrigerant with entrained oil from the accumulator to the lineconnecting the interchanger and evaporator, means for feedinganotherportion of refrigerant with entrained oil from a point above theliquid level in the accumulator to the interchanger responsive tosuction pressure and means for admitting said last portion ofrefrigerant, converted into gaseous form, and. oil entrained therewith,from the interchanger into the compressor.

6. In a system of the character described, an evaporator, a compressor,an accumulator, means for supplying refrigerant having oil entrainedtherein from the evaporator to the accumulator through an inlet to theaccumulator, a receptacle in the form of a cup positioned within andspaced from the walls of the accumulator, a suction line connected tothe receptacle and leading to the compressor said receptacle being sorelated to the inlet of the accumulator and to the walls of theaccumulator that some of the refrigerant and entrained oil dischargedinto the accumulator formsashallow pool of liquid in the receptacle andsome of the refrigerant and entrained oil forms a receptacle positionedabout the third line proximate the point of entrance of the refrigerantinto the .casing from the first line, means for withdrawing liquid fromthe casing through the second line, means for withdrawing refrigerant ingaseous condition from the casing through the third line and'means forfeeding a measured quantity of liquid refrigerant containing oil fromthe receptacle intothe third line.

10. In a system of the character described including a compressor, acondenser, an evaporator, an accumulator, a heat interchanger, means forfeeding liquid refrigerant from the condenser to the interchanger, andthen to the evaporator, means for admitting refrigerant from theevaporator to the accumulator, means for draining refrigerant from theaccumulator to the evaporator, some of the refrigerant admitted to theaccumulator being collected within the bottom of the accumulator, meansfor returning gaseous refrigerant from a point above the liquid level inthe accumulator to the interchanger, means, for admitting from theaccumulator a quantity of liquid refrigerant with entrained oil into thegaseous refrigerant fed to the interchanger, and a suction line forreturning gaseous refrigerant plus oil from the interchanger to thecompressor.

MERRIIL B. GODDARD. RICHARD c. earn

